水体中添加乳酸钙对中华绒螯蟹生长、蜕壳、钙沉积和水质指标的影响

Effects of adding calcium lactate to water on growth,molting,calcium deposition of Chinese mitten crab and water quality

为研究水体中添加乳酸钙对中华绒螯蟹幼蟹生长、蜕壳及体内钙沉积的影响,本研究分别在淡水中添加0、218、436和654 mg/L的乳酸钙,使水体中含有45.6、84.4、123.2和163.6 mg/L的钙离子(分别记为1#~4#组),对初始体质量为(4.78±0.51)g的中华绒螯蟹雌性幼蟹进行为期90 d(经历2个完整蜕壳周期)的养殖实验。结果表明:(1)随着水体乳酸钙浓度的增加,幼蟹的成活率显著上升;(2)随水体乳酸钙含量增加,第一次蜕壳后体质量、体质量增长率、特定生长率和肝胰腺指数均呈上升趋势,但差异不显著;而第二次蜕壳后幼蟹体质量、壳长和壳宽增长率均随着水体乳酸钙添加显著升高,其中3#组和4#组显著高于1#组;(3)添加乳酸钙对蜕壳间隔无显著差异,但可显著降低幼蟹的残肢率;(4)在钙沉积方面,添加乳酸钙可以显著提高幼蟹第一次蜕壳和第二次蜕壳阶段中血淋巴钙含量以及第一次蜕壳阶段幼蟹肌肉中的钙含量;(5)乳酸钙含量的增加可显著提高es EcR2和es RXR基因的表达丰度;(6)添加乳酸钙对水体pH、氨氮和亚硝酸盐无显著影响,而硬度和碱度随着乳酸钙含量增加而显著上升。综上,水体添加654 mg/L乳酸钙可提高幼蟹成活率、生长性能、组织中钙沉积和蜕壳相关基因表达丰度,并能降低幼蟹蜕壳后的残肢率。

In order to study the effects of calcium lactate to water on the growth,molt,and calcium deposition of juvenile Chinese mitten crab(Eriocheir sinensis),this study conducted a 90-day(two complete molting cycles)rearing experiment on female juvenile crabs with an initial body mass of(4.78±0.51)g.Calcium lactate was added to freshwater at concentrations of 0 mg/L,218 mg/L,436 mg/L and 654 mg/L and the calcium ion content in water is 45.6 mg/L,84.4 mg/L,123.2 mg/L and 163.6 mg/L.(recorded as Treatment 1#to 4#).The results showed:(1)The addition of calcium lactate improved survival rates of juvenile E.sinensis significantly.(2)With the increase in calcium lactate content,there was an upward trend of body mass,weight gain rate,specific growth rate,and hepatopancreas index of juvenile E.sinensis during the first molting cycle,but the differences were not significant.However,during the second molting cycle,the body weight,carapace length and carapace width growth rates of juvenile E.sinensis significantly increased with the calcium lactate addition,and among them,treatment 3#and 4#were significantly higher than treatment 1#.(3)The addition of calcium lactate had no significant effect on the intermolt duration but significantly reduced the rate of limb loss after each molting.(4)In terms of calcium deposition,the addition of calcium lactate significantly increased the calcium content in hemolymph during the first and second molting cycles,as well as calcium content in the muscle during the first molting cycle.(5)Increasing calcium lactate content significantly elevated the expression of es EcR2-mRNA and es RXR-mRNA.(6)Calcium lactate had no significant effect on water pH,ammonia nitrogen and nitrite,but water hardness and alkalinity significantly rose with increasing calcium lactate content.In summary,the addition of 654 mg/L calcium lactate to the water improved the survival,growth performance,calcium deposition in tissues,and expression of moltingrelated genes in juvenile E.sinensis,as well as reduced the limb loss rate after each molting.